The present invention concerns an exposure measuring element and an exposure device having such an element.
From Swiss Pat. No. 440,747 an exposure-measuring device is known which has a bar-shaped housing, one end portion of which is provided with front and rear window openings and with a photoelectric transducer which is movable into active position in front of the rear window opening while its other end portion is arranged for manipulating the device. The device can have means for swinging itself into the surface of a frosted glass plate.
Upon use, the end portion of the housing having the window openings is brought directly in front of or behind the frosted glass plate.
In the case of measurement in front of the frosted glass plate, the plane of the frosted glass plate is defocused as in the case of the known measurement cassette, so that refocusing is necessary upon each measurement. In the case of measurement behind the frosted glass plate, the measurement, which is dependent on the scattering angle of the frosted glass plate, is falsified.
The present invention is directed at remedying this. The invention, as characterized in the claims, solves the problem of creating an exposure-measuring device in which the measurement of the light takes place in the film plane and in which the handling of separate devices is unnecessary.
The advantages which can be obtained by the invention reside in the fact that a selective point-measurement or a differentiated integral measurement can be effected in the film plane, that a selective multi-point measurement can be carried out instead of a wide-field measurement, and that the average brightness range of the photograph can result from a single measurement.